Android Phone Won't reboot after rebooting using volume and power buttons?

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http://stackoverflow.com – So I was following this tutorial: http://forum.xda-developers.com/showthread.php?t=1830108 and I was following the last part of the tutorial for the bootloader and turned my device off and tried to reboot using the volume buttons and power button and it won't open up. It also cannot be seen by using the command adb devices thus I can't use any abd command to access it. What am I doing wrong? I am using a 7" smartfren Tablet called S7. (HowTos)